Sylvania



C. F. MILLER.

UNDERFEED STOKER ANO DRAFT CNTHOLLING MECHANISM THEHEOF. APPLmATmN mensuit. :9, 191s.

1 ,$352,466- Panted Sept. 14, 1920.

HIS ATTORNEYSIN FACT,

lunirse sTArEsirATENT "ortica, l

cHanLEsF. MILLER, or rI'rrsBUnGH, ynmxsYtvemn, AssIGNon To WESTING-HOUSE ELECTRIC s Menumcrunme COMPANY, A CORPORATION or PENN# SYLVANIA. l

UNDEBFEED s'roxnn AND DeAF'r-coN'rnoLmNs MECHANISM cinnamon.

To allulwmz'may concern: l

Beit known that I, CHARLES F. MILLER, a

citizen of the United States, and a resident of Pittsburgh, in thezcounty'of Allegheny and State of Pennsylvania, havemade a new and'useful Invention in Underfeed Stokers Y and Draft-Controlling MechanismVThereof, of which the following 4is a. specification.

This linvention relates to stokers, particu larly to under-feed stokersin which .the fuel is fed to the furnace at a surface of-the fuel bedr.4

- An object of this invention is to produce an improved Stoker of thetype described, in which new and improved means are employed forregulating draft to the furnace and at the same time for subjecting thegrate bars to the cooling influence of the incoming air.

A further object is to produce an improved Stoker of the type described,in' which improved means are employed for mounting both the moving andstationary grate bars, so that the fuel feeding retorts or troughs maybe removed without removing the grate bars or the fuel supportingmembers,V or interfering with their adjustment.

A further object is to produce a rate bar point` beneath the in whichimproved means are emp eyed for.

cooling the fuel supporting surfaces of the bar and at the same time fordelivering regulable amounts of air under pressure to different parts ofthe fuel bed.

A further object is to produce a fue] supporting element or a grate bar,in which means are employed for receiving air under pressure at -twodifferent points, and for de'- ivlering all of the air so received tothe fuel These and other objects which will be made apparent throughoutVthe further description of this invention, are attained by means ofapparatus embodying the features herein described, and illustrated inthe drawings Vaccompanying 4and forming apart hereof. Y H

In the drawings 'Figure l isatransverse, verticahsectional view of aStoker embody?V ing my invention, one-half being shown in section alongthe line A-A of 3, and the other, in section along the line B-B of thesame figure'. ,F ig. '2 is a' fragmental per-` spective viewillustrating the arrangement of air boxes employed in the Stoker embody-Snecilcatibn of Letters Patent.v Patented Sept. 14, 1920, ppimaup measeptember It,` 1ere'- 'seria'im 120,9?9,

.ing my invention and also illustrating the method of mounting and ofactuating'` tbc grate bars or fuel supporting elements.

Eig. Bis a fragmental perspective view of one air box. It yis well knownto employ a horizontal fuel retort or trough, which ex tends from thefront to the rear of tbc furnace, and into which fuel is forced by meansy of plungers or a revolving screw. It is also well known to employ sucha retort in connection with either inclined or horizontal fuelsupporting members, such as grate bars, which are located on bothsidesofthe retort and on topwliich fuel is fed from the retort by acrowding or upheaving action ofthe fuel, occasioned by the introductionof fresh fuel into the retort at a point below the surface of the -fuel,contained therein, or of the fuel, located on the fuel supportingmembers ofthe furnace. It is also old to employ movin@ and stationarygrate bars, in connection with such a retort, which coperateto 'agitateorbreak up the fuel bed and to gradually move the fuel from the retorttoward the outer end of the grate bars, or

toward the sides of the furnace. lt is also old to supply air underpressure to euch furnacesand to cause the air or blast to traverse air`passages formed within the grate bars or fuel supporting elements, but,so far as l lrnow, it is new to deliver all or substantially all of theair entering the furder pressure to the grate bars in two streams,

and to so construct the air or blast delivery passages of euch gratebai-'that each stream of air or blast will be delivered toarlilferentpart of thefuel bed. These novel feav tures form 4detallsorpart of my present in ve'ntion Ymeans of a; plunger, from a hopperreceptacle located at thefront and on the outside of the furnace.

The furnace also includes grate bars which are arranged in two sets, oneset being loe'ited on one side and the other set on the other side ofthe retort The grate bars of each set are mounted on two air boxes whichextend sulgistantially parallel to the retort and u liich supply air lopassages formed within the grate bars.

s illust ated the retort 3 extends lroni the trout to the rear of thel'urnarf '.inllis mounted on 'frames or pedestols i which are located atright angles to the longitudinal axis ot the retort and extendsubstantially across the furnace 'from our sil e lo the other. Thegirate hars or fuel supportin` elements 5 a re arranged in two sets, aset being located on each sido of 'the retort. 'The grr-ale bars of eachset areA supported by two air boxes 6 and 7, which are inountedon thepedestals L lt- \\ill oi' rou '3c be understood that tivo or morepedestszls arr employed and that they are so spaced along the retort asio provide a rigid support for the retort, the rute 'oars und ull theoperating;l parts ot the stoker.

is illust ated cach pedestal -l is provided with a recess, locatedmidway between ils ends und in which the retort Il is mounted. As shownthe retort consists of side walls 8 and a4 base plate 9. The side wallsextend vertically, with their lower ends engaging longitudinallyextending ribs l0, formed on thc pedestal, and they are bolted orotherwise secured to the pedestal. rlhe base plate 9 rests on the ribengaging anoes of the side walls S and is rigidly securell to thepedestals by Suitable nicans, not shown.

The air boxes 6 are located on opposite sides of the retort 3 and aremounted en the pedestal el in such positionsl that each supports theupper or inner ends oi' the grate bars of one set. Each air box 6 issubstantially rectangular in crossscction and is provided with alongitudinal extending air duet which communicates` with blast deliveryports l2 formed iu the bar supporting surface of the box.

The air boxes 7 are located near the side walls of the furnace and eachis so mounted on the pedestals l that it forms a. support for the loweror outer ends of the grate bars of one set. Each air box 7 issubstantially channel shaped in cross-section and is adapted to deliverair to the grate bars1 supported by it, through blast delivery ports 1.4formed in its bar supporting surface.

The pedestals 4 not only support the operating parts ot the Stoker butalso forni spacers Jfor the blast or air delivery passages of thestolzer. The space below the retort and fuel supporting elements ot thestolzer is divided into three compartments or into chambers l5, 16. and1G' by partition plates 17 which are mounted on the pedestals. Thechamber 15 may be termed the primary air chamber and, extending' fromthe liront to the rear of the Stoker, is adapted to deliver air underpressure to the air boxes 6 and T. This chamber communicates with ablast delivery passage 18, which is shown located immediately below theretort 3, consequently the air delivered through thopassa-ge 18 isdivided into two streams whiclrpafs to op posite sides of the furnace.

Air is delivered from the chamber l5 to the air boxes 6 through passagesor ports 19 provided in supporting lugs 20 which are formed on thepedestal. Each supporting lugr 'forms a journal or bearing [or a. rocksha lt 2l and alsosupports one air ooX illustrated each air box 6 isprovided witl a depending extension 22, in which` aport 23 is 'formedfor delivering air from one of` the passages 19 to the interior passageof the box. Each bell' (3 is also provided with lon gitudiuallyextending ribs 24 which are spaced to correspond to the space of thepedestal l and whichare eonsequentlg. located immediately above theinlet portsl 22 with which the box is provided. These ribs rngage theupper 'face oi' supporting lugs 2l) ot different pedestals and cachboxis adapt.- cd to be clamped to the outer lateral face of itssupporting lng by means of bolts or other suitable means so as to placethe ports4 23 of the box in direct communication with the passages 19 ofthe pedestlals.

The air boxes 7 are mounted on the pedestals l in such a way that theirHang-reextend downwardly and subtend upwardly projecting mounted lugs 25formed on the pedestal. lith this arrangement the open side of thechannel section ofeachbox 7 is in le ,-onnnunication with the.- chaniher15..4

'The grate bars 5 are substantially similar in erternal contour but;every other har ot cach set is adapted to reciprocate or to movefludinally toward und away from the retort. For this reason every otherbar is provided withV downwardly projecting prongs 26 which engage therock shaft 21 and through which the reeiprocatory motion, imparted bythe rock shaft, is transmitted to the bars. The stationary bars areprovided with downwardly extending lugs 27 which encrage oppositesidesof. the air box 6 and ho d the hars in place.

The air blast, delivered to the fuel bed, is rst passed through thegrate hars "or the purpose of cooling the grate bars and at'the Sametime preheating` the air. lnasniuclras each grate bar receives blastfrom two sources, namely, an airboxl'i. and an airbox 7, it is providedwith two air passages which, as illustrated7 deliver` air to differentparts of the fuel bed. Each port 120i the air boxes 6 communicates withair passage 28, formed in the retort end of one gratev bar. Each gratebar is therefore provided with an admission port, whichcornmunicateswith the passage 28 and which is formed in that portion of the bar whichengages the bar supporting surface of its supporting box '6.'

bers. 16 or 16, after the air haspassed' through the greater portion ofthe-bar. This is accomplished by providing an air 'delivery port 31, ineach bar, which is located near the partition, separating the passages3() and 28, and is adapted to discharge the air from the passage 30downvvardlyint'o one of the secondary air chambers. `The inlet port tothe passage 30 of each grate bar is formed in the face of the bar whichengages the air box 7. The air deliveryr passages ,of the stationary andmoving grate bars are similar. The ports 12 and 14 are so proportioned,With relation to the registering ports of the grate bars, that the flowof air into the movlng bars is not throttled by the reciprocati'on ofthe bars nor are the air ports in either the bars or the air boxesuncovered at any time during the motion of the bars,

The blast issuing from the ports 31 of the grate bars and entering thesecondary air chambers passes upwardly between the grate bars and isdelivered to that portion fof the fuel bed supported by them. For thisVreason the-bars are provided with spacing pads 33 which are located oneach side oi' each bar and at each end thereof.

During the operation of the Stoker fuel Y issuing from the retort ischstributed over both sets of grate bars and the fuel bed assumes acontoursomewhat similar to the dotted line in Fig. 1. The reen fuelenters the thickest portion of the nel bed and consequently it isdesirable to be able to control the supply of air to, this portion ofthe fuel bed independently of the air delivered to the thinner portionsof the bed, located on the grate bars. This is accomplished byproviding'a damper 34, in the primary air chamber 15 and between the airdelivery passage 18 and each air box 7. As illustratet these dampersextend from the front to the rear of the chamber 15 and may be operatedfrom the front of the furnace to cut down the air supply to the airboxes 7 and. consequently to the secondary air chambers and in this Waypermit the blast to the thicker portion of the fuel bed to be in-4creased Without the liability of blowing holes through the thinnerportion. The continuous delivery of fuel into ,the retortL causes thefuel to distribute itself over the grato bars 5 and finally to bedelivered on to dump grates 35, which are located on .each side of thefurnace and extend from the frontto the rear thereof. illustrated the'dump grates are pivotally .mounted on brackets 36 carried `by the airboxesj' and are located at the outer ends of the grate bars. Thereciprocating motion of the moving grate lbars aids the distributing offuel over the fuel supporting elements and also tends' to break up thefuel bed and feed the fuel downwardly along the'grate bars. `The ash andclinkers are discharged into the ash pit by lowering the dump gratos 35and as illustrated each furnace is provided With twoash pits one locatedat'cach side thereof.

`The secondary air chambers 16 and 16' receiveV all the coal or fuelYWhich may sift through the openings between the grate bars or throughthe openingsbetween the inner ends ofthe grate bars and the upper edgesof theretort. The pedestals dare so formed that each secondary airchamberis provided with two downwardly inclined Walls which terminate ina fiat floor 37.] Inasmuch as the secondary air chambers extend from thevfront to the rear of thefurnace the siftings may be readily removedtherefrom by providing a door for each secondary air chainber which maybe located in the front of'the furnace and may be of substantiall thesame Width as the floor 37. It will a so be apparent that'thisarrangement of the partition plates 17' prevents the coal siftings frominterfering with the operation of the Stoker, since there is no tendencyfor it to interfere with the operationof the rock shaft 2] nor -is thereany possibility of its entering the air chamber 15.

By supporting the grate bars on the air boxes it is possible to remove'the retort Without in any way interfering with the adjustment of thegrate bars and it is also possible to remove the grate bars and theiroperating mechanism without interfering with the op`- eration of theretort or its fuel feeding means.

The rock shaft 21 maybe operated by the usual form of stokerdrivemechanism, and,

it Will be apparent, While I have illustrated but one embodiment of mvpresent invention,

that various changes, modifications, substitutions, additionsy andomissions may be made in the apparatus illustrated 'Without departingfrom the `spirit and scope of the invention as set forth by the appendedclaims.

VVhat-I claim is:

1. An, underfeed stel-:er Comprising a rotort, and grate bars adapted-toreceive fuel from the retort, each grate bar being provided With twyeropenings at its retort end and a delivery passage communicatiu g there-Witlnand a separate air delivery portami a separate passagecommunicating therewith, means for dividing the space below the gratebars into a. primary and a secondary air chamber ant 'ineens fordelivering air from the primary air Vchamber to the separate passages ofeach grate bar, the said air delivery port being adapted to deliver airto the said secondary chamber.

2. An underfeed Stoker comprising a retort, and grate bars adapted toreceive li'uel ironi the retort, each grate bar being provided withtivrcr openings at its retort end and a delivery passage. ronnnunicatingtherewith, and a separate air delivery port and a separate passagecommunicating there with, means `For dividing the space below the gratebars into a primary and a secondary air chamber and means tor deliveringair from the primary` air chamber to the separate passages of eachgratebar, said secondary air chamber' receiving air through the ports formedin the grate bars, and eischarging theair between the grate bars intothe t'uel thereon.

An underfeed stolier comprising fuel feeding retort, grate sms receiving*fuel therefrom, an air chamber beneath the bars adapted to dischargeair between the bars into the fue-l thereon, each oi' the said barsbeing provided with a pair oi independent air passages, one of whichdischarges air into the said air chamber and two air boxes forsupporting the grate bars, one of which is adapted to deliver air to onepassage of each bar and the other of which is adapted to deliver air tothe other passage of the bar.

4. An underteed Stoker comprising a fuel feeding retort, grate barsreceiving Yfuel therefrom, an air chamber beneath the bars adapted todischarge air between the bars into the fuel thereon, each of the saidhars being provided with a pair of in-lrgianzlent air passages, one ofwhich disclinrgcs air into the said air chamber, pair oi air l :ers forsupporting the grate bars, one oi" which is adapted to deliver air toone iliassage of each bar and the other of which is adapted to deliverair to the other passage oli the bar, and means for controlling thedeliveryr of air through one of the said boxes;

5. An underfeed Stoker comprising a retort, grate bars adapted toreceive fuel from the retort and supporting means Jfor the retort' andgrate bars, each grate bar being provided at its retort end with twyeropenings, an air passage for delivering air thereto, and an inlet portcommunicating with the passage, each grate bar being provided with asecond inlet port located near the other end thereof, a passaffecommunicating,T .vith the second port and extending throughout thegreater portion of the bar and a delivery port located in the lower faceof the bar and communicating with the last mentioned passage.

G. A grate bar having twyer openings formed in one end thereof, a)assage former therein and communicating with the oper ing and having aninlet port communicating therewith, a second passage formed in the gratebar, a delivery `port located in the lower face of the bar,and'intermediate its ends, and communicating with the second passage,and an inlet port located in the opposite end of the bar from the ta'yeropenings and communicating with the second passage.

7. ln an underfced stoker, a iuel feeding retort, an ash dischargemechanism, a set oll grate bars located between the retort and saidmechanism, two air boxes, one located adjacent the ash dischargemechanism and one adjacent the retort ends of the bars 'for supportingthe bars and for delivering air under pressure to separate passagesformed within the bars, a primary air delivery chamber located beneaththe grate bars and communicating with each air box, a secondary airdelivery chamber located im niediatcly below the grate bars andreceiving air from the primary chamber through passages oi the gratebars.

S. An underfeed Stoker comprising a fuel feeding retort, a dump gratemechanism, a set ot grate bars located in parallel relation andextending from the retort to said incohanism, each grate bar beingprovided with two separate air delivery passages, onel having an inletat' one end of the bar and an outlet adjacent the opposite end oi thebar adapted to discharge air beneath the bar, and the other an inletintermediate the ends of the bar and outlet ports discharging into theiuel upon the bar, and two air boxes for supporting the grate bars andeach delirrriug air to a separate set o'lair passages o? the bars.

9. )in underfeed Stoker comprising a Yfuel feeding retortf a dump gratemechanism, a set ol' grate bars extending in parallel relation andlocated bet-Ween the retort and said mechanism, each grato bar beingprovided with two separate passages, one hav infr an inlet .locatedintermediate the ends of the bar, and communicating with twyers formedin the retort end of the bar, and the other having an inlet formed inthe ash discharge end of the bar and connnunicating with a delivery portformed in the lower face of the bar adjacent to the inlet to the Erstmentioned passage,two airboxes for supporting said grate bars, eachdelivering air under pressure to one of the inlets of everu bar,pedestals on which said retort and air boxes are mounted, and partitionplates mounted on the pedestal and dividing the space below the barsinto a prin'iary air chamber communicating directly with both air boxes,and a4 secondary air chamber located immediately below the grate barsand receiving air from the air delivery ports located in the bottom ofthe grate bars.

i0. An underfeed Stoker comprising a centrally located retort, an ashdischarge mechanism located on each side of the retort and extendingparallel therewith, a separate set of grate bars located on each side ofsaid retort and each extending from the retort toward an ash dischargemechanism, each grate bar being provided with two separate air passages,one having an inlet formed near the ash discharge end of the bar and anair delivery port iiormed in the lower face of the bar intermediate theends thereoithe other passa-ge having an inlet formed near the retortend of the bar and communicating with twyer openings located in theretort end of the bar, two air boxes for supporting each set of gratebars, each delivering air to one inlet or each bar of one set, apedestal on which Said retort and all said air boxes are mounted, andpartition plates mounted on tlie'pedestal and dividing the space belowthe furnace into a primary air chamber, 'which communicates with all theair boxes, and two secondary chambers, each being below one set oi'grate bars and receivingair from the air delivery ports of the barsunder which it is located., 1

1l. An underieed Stoker comprising la central retort, two ash dischargemechanisms, one located on each side of the retort and extendingsubstantially parallel therewith, a separate set of grate bars betweenthe retort and each o4 said mechanisms, each grate bar having twoseparate air passages formed therein, one having an inlet at tie ashdischarge end of the bar and communicating with an air delivery portlocated in the bottom of the bar intermediate the ends thereof, theother having an inlet located intermediate the ends of thc bar andcommunicating with twyer openings located in the retort end of the bar,two air boxes on which each set of grate bars is mounted, eachcommunicating with one inlet of each bar supported thereon, a pedestalon which all the air boxes are mounted, partition plates mounted on thepedestal and dividing the space below the air box into a primary airchamber which communicates with all the air boxes, and 4two secondaryair chambers, each of which communicates with the air delivery portsofthe bars under which it is located, and Vmeans for separatelycontrolling the delivery of ai secondary air chamber. Y

V communicating inlet registered located immediately f comminiicatingwith 4pedestal structure,

to each l2. ln combination y projecting lug formed thereon provided withan' air deliverypassage, partition plates mounted on the' pedestalvforming an air chamber with the said passage, an air box mounted onsaid lug and having an with the said passage, and grate bars supported,on said air box provided with air assages adapted to receive airirom thesai box. i

13. An underfeed stolzer comprising a fuel feeding'retort, grate barsreceiving uel therefrom, an air chamber beneath the bars adapted todischarge air between the bars into the fuel thereon, each bar beingprovided with Aa pair of independent air passages, one of which isadapted to discharge air into the said chamber and the other of which isadapted to discharge air into the fuelupon the bar,l and a separate airbox eachv passage of the grate barand 'adapted to deliver air to the fpassage in communication therewith.

stoker comprising a 14;'A`n nderfeed pedestal construction havingsupporting elements Vfor two groups of grate bars and an intermediateretort, a ricd bysaid retort supporting elements, and a group ofremovable grate bars supported by said grate bar supporting elements ateach` side of the retort.

l5. An underfeed Stoker comprising a a central retort, grate barsremovably carried by said pedestal structure` wall elements carried bysaid Y in an underfeed` Stoker, a retort, ,a pedestalfsupporting theretort and `having an upward removable retort car pedestal structureand, together with the reg tort, deiininga primary air chamber, the

wall elements beneath'the grate bars defining secondary air chambers,each grate bar having independent passage-ways communicatingwith theprimary air chamber, one discharging continuous to the retort dischargeand the other discharging into a` secondary air chamber, said secondaryair chambers beingcovered Vby the grate bars whereby the preheated airtherein may escape between bars to support combustion.

mln testimony whereof I have hereunto subscribed my naine this 18th dayof September, 1916.

.l CHARLES F. MILLER.

